The present disclosure relates to intraocular lenses.
There have been several intraocular lens models designed to allow patients to see at all distances following lens extraction. The most commonly used of these are the multifocal lenses, where the optic in the intraocular lens has two or three focal lengths. These lenses have problems since they require the patient to visually select the lens component's focal length appropriate to the target in their sight.
Since the lenses have multiple focal lengths, only a fraction of the light is available at the focal length being observed. This results in loss of contrast sensitivity.
The multiple focal lengths also cause dysphotopsias, especially at night when glare and halos are present. This has led to many multifocal lenses being explanted.
Other lenses which have been characterized as accommodating lenses have also been developed. Constriction of the ciliary muscle during accommodation has been believed to cause an increase in pressure in the posterior, the vitreous cavity of the eye, and a reduction of the pressure in the anterior chamber of the eye. These pressure changes have been believed to cause the optic of a flexible intraocular lens to move forwards and backwards in response to the pressure changes. This has been believed to allow the patient to see seamlessly at all distances. Such designs, however, can be improved.